Wire grid polarizer with slanted support-ribs

ABSTRACT

A wire grid polarizer (WGP) can include an array of support-ribs on a substrate. Sides of the support-ribs can be inclined to one side. A wire can be applied on an upper-side and distal end of each support-rib, each wire being separate from wires on adjacent support-ribs. The WGP can be made with reduced or no etching.

CLAIM OF PRIORITY

This application claims priority to: U.S. Provisional Patent ApplicationNo. 62/892,135, filed on Aug. 27, 2019; U.S. Provisional PatentApplication No. 62/894,484, filed on Aug. 30, 2019; and to U.S.Provisional Patent Application No. 62/949,568, filed on Dec. 18, 2019;all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present application is related generally to wire grid polarizers.

BACKGROUND

A wire grid polarizer (WGP) can divide light into two differentpolarization states, One polarization state can primarily pass throughthe WGP and the other polarization state can be primarily absorbed orreflected. The effectiveness or performance of WGPs is based on hightransmission of a predominantly-transmitted polarization (sometimescalled Tp) and minimal transmission of an opposite polarization(sometimes called Ts). It can be beneficial to have high contrast(Tp/Ts). Contrast can be improved by increasing transmission of thepredominantly-transmitted polarization (e.g. increasing Tp) and bydecreasing transmission of the opposite polarization (e.g. decreasingTs). It would be advantageous to improve performance of WGPs.

Ribs of high-performance WGPs, especially for polarization of visible orultraviolet light, and ribs of other optical devices, can be small anddelicate with nanometer-sized pitch, wire-width, and wire-height. It canbe costly to manufacture such WGPs and other optical devices. It wouldbe advantageous to discover less costly manufacturing methods foroptical devices.

Patterning and etching can form wires of the WGP. Some desirablematerials for wire grid polarizers can be difficult or impractical toetch. It would be beneficial to reduce or eliminate the need for etchingto form the wires.

SUMMARY

It has been recognized that it would be advantageous to improveperformance of wire grid polarizers (WGPs), to discover less costlymethods for manufacture of WGPs, and to reduce or eliminate the need foretching such WGPs. The present invention is directed to variousembodiments of WGPs, and methods of making WGPs, that satisfy theseneeds. Each embodiment may satisfy one, some, or all of these needs.

The WGP can include an array of support-ribs on a substrate. Sides ofthe support-ribs can be inclined to one side. There can be a wire on anupper-side and a distal end of each support-rib, each wire beingseparate from wires on adjacent support-ribs.

BRIEF DESCRIPTION OF THE DRAWINGS (DRAWINGS MIGHT NOT BE DRAWN TO SCALE)

FIG. 1 is a schematic, cross-sectional side-view illustrating a step 10in a method of making a wire grid polarizer (WGP), including applying anuncured layer 12 on a substrate 11, in accordance with an embodiment ofthe present invention.

FIG. 2 is a schematic, cross-sectional side-view illustrating a step 20,which can follow step 10, in a method of making a WGP, includingimprinting support-ribs 22 in the uncured layer 12, in accordance withan embodiment of the present invention.

FIG. 3 is a schematic, cross-sectional side-view illustrating a step 30,which can follow step 20, in a method of making a WGP, including curingthe uncured layer 12 to form a cured layer 32, in accordance with anembodiment of the present invention.

FIG. 4 is a schematic, cross-sectional side-view illustrating a step 40,which can follow step 30, in a method of making a WGP, includingremoving the mold or stamp 13, leaving support-ribs 22 in the curedlayer 32 with channels 41 between adjacent support-ribs 22, inaccordance with an embodiment of the present invention.

FIG. 5 is a schematic, cross-sectional side-view illustrating a step 50,which can follow step 40, in a method of making a WGP, includingdepositing a cap 52 on each support-rib 22, each cap 52 extending downsides S of the support-rib 22, in accordance with an embodiment of thepresent invention.

FIG. 6a is a schematic, cross-sectional side-view illustrating a step 60a, which can follow step 40, in a method of making a WGP, includingdepositing a wire 62 on each support-rib 22, each wire 62 extending downsides S of the support-rib 22, in accordance with an embodiment of thepresent invention.

FIG. 6b is a schematic, cross-sectional side-view illustrating a step 60b, which can follow step 50, in a method of making a WGP, includingdepositing a wire 62 on each cap 52, each wire 62 extending down sides Sof the cap 52, in accordance with an embodiment of the presentinvention.

FIG. 7 is a schematic, cross-sectional side-view illustrating a step 70,which can follow step 60 a or 60 b, in a method of making a WGP,including depositing a lower rib 72 on each wire 62, each lower rib 72extending down sides S of the wire 62, in accordance with an embodimentof the present invention.

FIG. 8 is a schematic, cross-sectional side-view illustrating a step 80,which can follow step 70, in a method of making a WGP, includingdepositing a top rib 82 on each lower rib 72, each top rib 82 extendingdown sides S of the lower rib 72, in accordance with an embodiment ofthe present invention.

FIG. 9 is a schematic, cross-sectional side-view of an optical device 90including an array of parallel, elongated support-ribs 92 on a face 11_(f) of a substrate 11, and sides 92 _(i) and 92 _(u) of thesupport-ribs 92 inclined to one side, in accordance with an embodimentof the present invention.

FIG. 10 is a schematic perspective-view of the optical device 90 of FIG.9, in accordance with an embodiment of the present invention.

FIG. 11 is a schematic, cross-sectional side-view of an optical device110, similar to optical device 90, except that for optical device 110,external angles A_(pi) and A_(pu) at the proximal end 92 _(p) aresimilar in value to internal angles A_(di) and A_(du), respectively, atthe distal end 92 _(d), in accordance with an embodiment of the presentinvention.

FIG. 12 is a schematic, cross-sectional side-view of an optical device120, similar to other optical devices described herein, providingguidance how angles A_(pi), A_(pu), A_(di), and A_(du) are defined orinterpreted, particularly if the sides 92 _(i) and 92 _(u) are curved,if the face 11 _(f) of the substrate 11 is rough or curved, if thedistal end 92 _(d) is curved, or combinations thereof, in accordancewith an embodiment of the present invention.

FIG. 13 is a schematic, cross-sectional side-view of an optical device130, such as for example a wire grid polarizer (WGP), similar to opticaldevices 90 and 110, but optical device 130 further comprising a wire 132on the upper-side 92 _(u) and the distal end 92 _(d) of each support-rib92, in accordance with an embodiment of the present invention.

FIG. 14 is a schematic, cross-sectional side-view of an optical device140, similar to optical device 130, but optical device 140 furthercomprising some of the wire 132 on the inner-sides 92 _(i) of thesupport-ribs 92, with maximum thickness Th_(132i), and some of the wire132 on the face 11 _(f) of the substrate 11 in the channels 93, withmaximum thickness Th_(132s), in accordance with an embodiment of thepresent invention.

FIG. 15 is a schematic, cross-sectional side-view of an optical device150, similar to optical devices 130 and 140, but optical device 150further comprising a cap 152 on the upper-side 92 _(u) and the distalend 92 _(d) of each support-rib 92 and sandwiched between the wire 132and the support-rib 92, in accordance with an embodiment of the presentinvention.

FIG. 16 is a schematic, cross-sectional side-view of an optical device160, similar to optical device 150, but optical device 160 furthercomprising some of the cap 152 on at least part of the inner-sides 92_(i) of the support-ribs 92, in accordance with an embodiment of thepresent invention.

FIG. 17 is a schematic, cross-sectional side-view illustrating a step170 in a method of making an optical device, including applying anuncured layer 172 on a face 11 _(f) of a substrate 11, in accordancewith an embodiment of the present invention.

FIG. 18 is a schematic, cross-sectional side-view illustrating a step180 in a method of making an optical device, which can follow step 170,including imprinting a pattern of uncured support-ribs 182 in theuncured layer 172 with sides 182 _(i) and 182 _(u) of the uncuredsupport-ribs 92 inclined to one side, in accordance with an embodimentof the present invention.

FIG. 19 is a schematic, cross-sectional side-view illustrating a step190 in a method of making an optical device, which can follow step 180,including curing the uncured layer 172 to form solid, cured support-ribs92, in accordance with an embodiment of the present invention.

FIG. 20 is a schematic, cross-sectional side-view illustrating a step200 in a method of making an optical device, which can follow step 190,including removing a stamp 171 at an oblique angle A₁₇₁ with respect tothe face 11 _(f) of the substrate 11, in accordance with an embodimentof the present invention.

FIG. 21 is a schematic, cross-sectional side-view illustrating a step210 in a method of making an optical device, which can follow step 170(but with different shaped stamp-ribs 171 _(r) than illustrated in FIG.17), including imprinting a pattern of uncured support-ribs 182 in theuncured layer 172 with sides 182 _(i) and 182 _(u) of the uncuredsupport-ribs 92 inclined to one side, in accordance with an embodimentof the present invention.

FIG. 22 is a schematic, cross-sectional side-view illustrating a step220 in a method of making an optical device, which can follow step 210,including curing the uncured layer 172 to form solid, cured support-ribs92, in accordance with an embodiment of the present invention.

FIG. 23 is a schematic, cross-sectional side-view illustrating a step230 in a method of making an optical device, which can follow any ofsteps 190, 200, or 220, including applying a conformal layer 231 oncured support-ribs 92, in accordance with an embodiment of the presentinvention.

DEFINITIONS

The following definitions, including plurals of the same, applythroughout this patent application.

As used herein, the term “conformal layer” means a thin film whichconforms to the contours of feature topology. For example, a thicknessacross the entire conformal layer can have a minimum value ≥1 nm and amaximum value ≤20 nm. As another example, the maximum value divided bythe minimum value ≥1 nm of the thickness of the conformal layer can be≤20, ≤10, ≤5, or ≤3. As another example, the conformal layer at a distalend of each wire can be separate from the conformal layer at a distalend of adjacent wires, the distal end being a farthest end of the wiresfrom the substrate.

As used herein, the term “elongated” means that a length (length of theribs into the page) is substantially greater than width or thickness(e.g. length can be ≥10 times, ≥100 times, ≥1000 times, or ≥10,000 timeslarger than width, thickness, or both).

As used herein, the term “nm” means nanometer(s).

As used herein, the term “normal angle deposition” means deposition atan angle of 90°+/−10° with respect to a plane 133 of a surface on whichthe material is deposited. See FIG. 13.

As used herein, the term “on” means located directly on or located abovewith some other solid material between.

As used herein, the term “parallel” means exactly parallel, parallelwithin normal manufacturing tolerances, or nearly parallel, such thatany deviation from exactly parallel would have negligible effect forordinary use of the device.

As used herein, the same material composition between different parts ofthe WGP means exactly the same, the same within normal manufacturingtolerances, or nearly the same, such that any deviation from exactly thesame would have negligible effect for ordinary use of the device.

Unless explicitly noted otherwise herein, all temperature-dependentvalues are such values at 25° C.

Materials used in optical structures can absorb some light, reflect somelight, and transmit some light. The following definitions distinguishbetween materials that are primarily absorptive, primarily reflective,or primarily transparent. Each material can be considered to beabsorptive, reflective, or transparent in a wavelength range of intendeduse, across the ultraviolet spectrum, across the visible spectrum,across the infrared spectrum, or combinations thereof, and can have adifferent property in a different wavelength range. Materials aredivided into absorptive, reflective, and transparent based onreflectance R, the real part of the refractive index n, and theimaginary part of the refractive index/extinction coefficient k.Equation 1 is used to determine the reflectance R of the interfacebetween air and a uniform slab of the material at normal incidence:

$\begin{matrix}{R = \frac{\left( {n - 1} \right)^{2} + k^{2}}{\left( {n + 1} \right)^{2} + k^{2}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$Unless explicitly specified otherwise herein, materials with k≤0.1 inthe wavelength range are “transparent” materials, materials with k>0.1and R≤0.6 in the specified wavelength range are “absorptive” materials,and materials with k>0.1 and R>0.6 in the specified wavelength range are“reflective” materials. If explicitly so stated in the claims, materialswith k>0.1 and R≥0.7, R≥0.8, or R≥0.9, in the specified wavelengthrange, are “reflective” materials.

As used herein, the ultraviolet spectrum means≥10 nm & <400 nm, thevisible spectrum means≥400 nm & <700 nm, and the infrared spectrummeans≥700 nm & ≤1 mm.

DETAILED DESCRIPTION

Five or six support-ribs 22 or 92 are illustrated in the figures anddescribed herein, but there can be many more support-ribs 22 or 92 thansix, or there can be fewer support-ribs 22 or 92 than five, such as forexample two or three, particularly if the optical device is a waveguide.

First Method, FIGS. 1-8

A first method of making a wire grid polarizer (WGP), illustrated inFIGS. 1-8, can comprise some or all of the following steps, which can beperformed in the following order or other order if so specified. Theremay be additional steps not described below. These additional steps maybe before, between, or after those described. The WGP can be formedwithout etching.

The first method can comprise: step 10 (FIG. 1), applying an uncuredlayer 12 on a substrate 11; step 20 (FIG. 2), imprinting support-ribs 22in the uncured layer 12 with a stamp 13; step 30 (FIG. 3), curing theuncured layer 12 to form a cured layer 32; and step 40 (FIG. 4),removing the stamp 13, leaving support-ribs 22 in the cured layer 32with channels 41 between adjacent support-ribs 22. Each support-rib 22can be connected to adjacent support-ribs 22 by material of thesupport-ribs 22.

In one embodiment, the uncured layer 12 can be a liquid with solidinorganic nanoparticles dispersed throughout a continuous phase, and thecured layer 32 can include a solid, interconnecting network of theinorganic nanoparticles. In another embodiment, the uncured layer 12 canbe a colloidal suspension including a dispersed phase and a continuousphase, and curing the uncured layer 12 can include removing thecontinuous phase to form a solid, defining the cured layer 32.

In another embodiment, the uncured layer 12 can be a solution includingmolecules in a solvent. The solvent can include water and an organicliquid. The molecules can include metal atoms bonded to reactive groups.Each reactive-group can be —Cl, —OR¹, —OCOR¹, or —N(R¹)₂. Each R¹ can bean alkyl group, such as for example —CH₃, —CH₂CH₃, or —CH₂CH₂CH₃. Curingthe uncured layer 12 can include reacting the molecules to form a solidof the metal atoms interconnected with each other, defining the curedlayer 32.

The first method can further comprise depositing an upper rib 53, or astack of upper ribs 53, on the distal end D of each of the support-ribs22 (see steps 50, 60 a or 60 b, 70, 80, or combinations thereof in FIGS.5-8). Example combinations of these steps, following steps 10, 20, 30,and 40, include: step 50; steps 50 then 60 b; steps 50, 60 b, then 70;steps 50, 60 b, 70, then 80; step 60 a; steps 60 a then 70; steps 60 a,70, then 80.

Step 50 can include depositing a cap 52 on each support-rib 22 at adistal end D of each support-rib 22 farthest from the substrate 11. Thecap 52 can be sputter deposited. The cap 52 can be transparent (e.g.across the ultraviolet spectrum, across the visible spectrum, across theinfrared spectrum, or combinations thereof).

The cap 52 can be wider than the support-rib 22 at or near the distalend D in order to block part or all of the channels 41, and thusminimize or prevent later-deposited upper ribs 53 from being depositedin the channels 41. For example, 1.1≤W_(C)/W_(SR), 1.2≤W_(C)/W_(SR),1.4≤W_(C)/W_(SR), 1.6≤W_(C)/W_(SR), 1.8≤W_(C)/W_(SR), or1.9≤W_(C)/W_(SR); and W_(C)/W_(SR)≤2.1, W_(C)/W_(SR)≤2.4,W_(C)/W_(SR)≤2.8, W_(C)/W_(SR)≤3.5, W_(C)/W_(SR)≤4, or W_(C)/W_(SR)≤6,where W_(C) is a width of the cap 52 measured at the distal end D of thesupport-rib 22, and W_(SR) is a width of the support-rib 22 measured at20% of a distance from the distal end D of the support-rib 22 towards aproximal end P of the support-rib 22 closest to the substrate 11.

Step 60 a can follow step 40 and can include depositing a wire 62 oneach support-rib 22 at a distal end D of each support-rib 22 farthestfrom the substrate 11. Step 60 b can follow step 50 and can includedepositing a wire 62 on each cap 52. Example deposition methods of thewire 62 include sputter deposition or evaporation deposition. The wire62 can be reflective (e.g. across the ultraviolet spectrum, across thevisible spectrum, across the infrared spectrum, or combinationsthereof). Steps 60 a and 60 b can be performed before or after thefollowing steps 70 and 80.

Step 70 can follow step 60 a or step 60 b and can include depositing alower rib 72 on each wire 62. The lower rib 72 can have a real part of arefractive index n_(L)≤1.6, n_(L)≤1.5, n_(L)≤1.4, n_(L)≤1.3, orn_(L)≤1.2 and an extinction coefficient k_(L)≤0.1, k_(L)≤0.01, ork_(L)≤0.001. Step 80 can follow step 70 and can include depositing a toprib 82 on each lower rib 72. The top rib 82 can have a real part of arefractive index n_(T)≥1.6, n_(T)≥1.7, n_(T)≥1.9, n_(T)≥2.1, orn_(T)≥2.3 and an extinction coefficient k_(T)≤0.1, k_(T)≤0.01, ork_(T)≤0.001. The refractive indices and extinction coefficients of thisparagraph can be such values across the ultraviolet spectrum, across thevisible spectrum, across the infrared spectrum, or combinations thereof.

Depositing the stack of upper ribs 53 can include depositing the upperribs 53 such that one, some, or all of the upper ribs 53 are separatefrom associated upper ribs 53 on adjacent support-ribs 22. A bottom 41_(b) of the channels 41 can be free of material of the upper ribs 53.The bottom 41 _(b) of the channels 41 can be free of material of thecaps 52, the wires 62, the lower ribs 72, the top ribs 82, orcombinations thereof. Depositing the caps 52 can include depositing eachcap 52 such that it is separate from caps 52 on adjacent support-ribs22. Depositing the wires 62 can include depositing each wire 62 suchthat it is separate from wires 62 on adjacent support-ribs 22.Depositing the lower ribs 72 can include depositing each lower rib 72such that it is separate from lower ribs 72 on adjacent support-ribs 22.Depositing the top ribs 82 can include depositing each top rib 82 suchthat it is separate from top ribs 82 on adjacent support-ribs 22.Deposition of any of the upper ribs 53 with separation from associatedupper ribs 53 on adjacent support-ribs 22 can be achieved as describedin the “FIRST AND SECOND METHODS, WIRE SEPARATION” section below.

The support-ribs 22, the upper ribs 53, the caps 52, the wires 62, thelower ribs 72, the top ribs 82, or combinations thereof, can have acurved cross-sectional shape at a distal end D farthest from thesubstrate 11. This curved cross-sectional shape can be a parabolic orhalf-elliptical cross-sectional shape. The curved cross-sectional shapecan improve WGP performance, such as by increasing transmission of apredominantly-transmitted polarization.

The cap 52 can extend down sides S of the support-rib 22, the wire 62can extend down sides S of the cap 52, the lower rib 72 can extend downsides S of the wire 62, the top ribs 82 can extend down sides S of thelower ribs 72, or combinations thereof. The curved cross-sectional shapecombined with the upper ribs 53 extending down sides of the lower,adjacent rib in the stack can improve manufacturing throughput becausethis shape can allow a thinner layer to achieve the same polarizationeffect.

The support-ribs 22 can have a low index of refraction (n₂₂) forimproved optical performance, especially at low wavelengths, such as forexample: n₂₂≤1.4, n₂₂≤1.3, n₂₂≤1.2, or n₂₂≤1.1. Furthermore, the indexof refraction (n₂₂) of the support-ribs 22 can be less than an index ofrefraction (n₁₁) of the substrate 11, less than an index of refraction(n₅₂) of the cap 52, or both.

One way of achieving this low index of refraction is to include smallvoids or cavities in the cured layer 32. These small voids, filled withair, lower the overall index of refraction of the cured layer 32. Forexample, the cured layer 32 can include silicon dioxide, with an indexof refraction of around 1.4-1.5, but with the voids, the overall indexof refraction can be <1.4. These voids can be formed by use of a solventin the uncured layer 12 which has larger molecules. For example, achemical in a solvent in the uncured layer 12 can have a molecularweight of ≥70 g/mol, ≥80 g/mol, ≥90 g/mol, ≥100 g/mol, or ≥110 g/mol. Asanother example, a chemical in this solvent can have a large number ofatoms in each molecule, such as for example ≥15 atoms, ≥20 atoms, or ≥25atoms. It can be useful for chemicals in this solvent to not have toohigh of a molecular weight so that it can be sufficiently volatile,Therefore, all chemicals this solvent can have a molecular weight of≤125 g/mol, ≤150 g/mol, ≤175 g/mol, ≤200 g/mol, or ≤300 g/mol. Allmolecules in this solvent can include ≤30 atoms, ≤50 atoms, or ≤75atoms. Further, this solvent can have a structure which occupies largerspace, such as an aryl molecule or otherwise a molecule with doublebonds. For example, the uncured layer 12 can include benzene or xylene.Thus, the support-ribs 22 can include organic moieties. For example,≥0.1%, ≥1%, or ≥10% and ≤15%, ≤25%, or ≤50% of atoms in the support-ribs22 can be part of organic moieties.

The support-ribs 22 and the caps 52 can have the same or similarmaterial composition. For example, ≥60%, ≥75%, ≥85%, or ≥90%; and ≤92%,≤95%, or ≤99%; of a material composition of the support-ribs 22 can bethe same as a material composition of the caps 52. An inorganic portionof the support-ribs 22 can be the same as an inorganic portion of thecaps 52. Thus, a difference in the material composition between thesupport-ribs 22 and the caps 52 can be added organic moieties in thesupport-ribs 22.

First Optical Device, FIGS. 5-8

A wire grid polarizer (WGP) can be formed by the first method describedabove, and consequently can include a broader variety of materials (eventhose difficult to etch) and thus potentially improved performance,durability, or both. The WGP can also be made at a lower cost due toavoidance or reduction of etch. The WGP, and components of the WGP, canhave properties as described above.

As illustrated in FIGS. 5-8, the WGP can include an array ofsupport-ribs 22 on a substrate 11, and an upper rib 53 or a stack ofupper ribs 53 on the distal end D of each of the support-ribs 22. Thesupport-ribs 22 and the stack of upper ribs 53 can be parallel andelongated, with a length extending into the pages of the drawings.Alternatively, the support-ribs 22 and the stack of upper ribs 53 canextend in variable directions, like a metamaterial polarizer forexample.

The upper rib 53 or a stack of upper ribs 53 can include one upper rib53 (FIGS. 5 and 6 a), two upper ribs 53 (FIG. 6b ), three upper ribs 53(FIG. 7), four upper ribs 53 (FIG. 8), or >four upper ribs 53. In oneembodiment, the stack of upper ribs 53 can include the following upperribs 53 in the following order moving outwards from the support-ribs 22:the cap 52, the wire 62, the lower rib 72, and then the top rib 82. Inanother embodiment, the stack of upper ribs 53 can include the followingupper ribs 53 in the following order moving outwards from thesupport-ribs 22: the wire 62, the lower rib 72, and then the top rib 82.In another embodiment, the upper rib 53 can include the wire 62.

Second Optical Device, with Slanted Support-Ribs 92

As illustrated in FIGS. 9-16 and 23, optical devices 90, 110, 120, 130,140, 150, 160, and 230 are shown comprising an array of parallel,elongated support-ribs 92 on a face 11 _(f) of a substrate 11 withchannels 93 between adjacent support-ribs 92. Each support-rib 92 canhave a cross-sectional profile with a proximal end 92 _(p) closest tothe substrate 11 and a distal end 92 _(d) opposite of the proximal end92 _(p). The distal end 92 _(d) can be farthest from the substrate 11.Each support-rib 92 can also have sides 92 _(i) and 92 _(u) facing thechannels 93 and extending from the proximal end 92 _(p) to the distalend 92 _(d). The channels 93 can include an air-filled region extendingalong a length of the channels 93, the length of the channels 93 being alongest dimension of the channels.

As illustrated in FIGS. 13-16, optical devices 130, 140, 150, and 160can each be a wire grid polarizer (WGP) with a wire 132 on theupper-side 92 _(u) and the distal end 92 _(d) of each support-rib 92.The wires 132 can be parallel and elongated. To facilitate polarization,each wire 132 can be separate from wires 132 on adjacent support-ribs92. The following discussion of the shape of the support-ribs 92 and theadded cap 152 can be helpful for ensuring or improving separation ofwires 132 on separate support-ribs 92, even with wire 132 depositionfrom normal incidence (see FIG. 13).

The sides of the support-ribs 92 can include an inner-side 92; whichleans towards and faces the substrate 11, and an upper-side 92 _(u),opposite of the inner-side 92 _(i) and not facing the substrate 11 orfacing away from the substrate 11. This leaning or slanting of thesupport-ribs 92 can facilitate deposition of wires 132 (particularly bynormal-angle deposition) on the upper-side 92 _(u), on the distal end 92_(d), or both, with each wire 132 being separate from wires 132 onadjacent support-ribs 92. In one embodiment, all support-ribs 92 canlean in a single direction.

The lean or slant of the support-ribs 92 can be quantified by anglesA₉₂, A_(pi), and A_(pu). Angle A₉₂ is a smallest angle between a plane95 (FIGS. 9-12) and the face 11 _(f) of the substrate 11. The plane 95extends along a length L (FIG. 10) of each support-rib 92 through acenter of the support-rib 92 from the proximal end 92 _(p) to the distalend 92 _(d). Example values for A₉₂ include 5°≤A₉₂, 15°: A₉₂, 25°≤A₉₂40°≤A₉₂, or 60°≤A₉₂; and A₉₂≤45°, A₉₂≤60°, A₉₂≤75°, or A₉₂≤85°. AP, isan external angle between the inner-side 92 _(i) and the face 11 _(f) ofthe substrate 11. Example values for A_(pi) include 5°≤A_(pi),15°≤A_(pi), 25°≤A_(pi), 35°≤A_(pi), 45°≤A_(pi), 55°≤A_(pi), or65°≤A_(pi); and A_(pi), 45°, A_(pi)≤55°, A_(pi), ≤65°, A_(pi)≤75°, orA_(pi)≤85°. A_(pu) is an external angle between the upper-side 92 _(u)and the face 11 _(f) of the substrate 11. Example values for A_(pu)include 95°≤A_(pu), 105°≤A_(pu), 115°≤A_(pu), 130°≤A_(pu), or150°≤A_(pu); and A_(pu) 135°, A_(pu) 150°, A_(pu)≤165°, or A_(pu)≤175°.A_(pi)−A_(pu) can be related as follows: |180°−A_(pi)−A_(pu)|≤2°,|180°−A_(pi)−A_(pu)|≤5°, |180°−A_(pi)−A_(pu)|≤10°,|180°−A_(pi)−A_(pu)|≤20°, or |180°−A_(pi)−A_(pu)|≤30°.

If the optical device is a wire grid polarizer (WGP) with wires 132,then angles A₉₂, A_(pi), and A_(pu) can be selected, along with size andspacing between the support-ribs 92, to keep each wire 132 separate fromwires 132 on adjacent support-ribs 92. In the following equation, L_(c)(FIG. 9) is a straight-line distance, from one support-rib 92 to anadjacent support-rib 92 in the channel, parallel to the face 11 _(f) ofthe substrate 11, and L_(i) (FIG. 9) is a straight-line distance of theinner-side 92 _(i) from the proximal end 92 _(p) to the distal end 92_(d). Typically, L_(c) is selected based on needed WGP performance (e.g.balance of Tp and Ts), and L_(i) is selected based on needed support-rib92 structural strength. Angle A₉₂ can then be calculated from thefollowing equation: A₉₂=cos⁻¹(L_(c)/L_(i)). This value of A₉₂ can resultin the support-ribs 92 blocking the face 11 _(f) of the substrate 11 inthe channels 11 from normal angle deposition of the wires 132. It mightnot be needed or desirable to achieve the exact A₉₂ value noted above.Variation from such angle can be quantified by the equationA₉₂=cos⁻¹(X·L_(c)/L_(i)). Values of “X” for different circumstances aredescribed in the following two paragraphs.

Partial blocking of the channels 11 might be acceptable, if somedeposition of the wires 132 in the channels 93 is allowed in thespecific WGP design, or if deposition is performed at an oblique anglewith deposition target facing the upper-side 92 _(u). Example ranges ofX, for use in the equation A₉₂=cos⁻¹(X·L_(c)/L_(i)), include X≤0.95,X≤0.9, X≤0.8, X≤0.7, X≤0.6, X≤0.5, X≤0.4, or X≤0.2.

For some designs, particularly for high transmission of thepredominantly-transmitted polarization (e.g. high Tp), partial coverageof the upper-side 92 _(u), the distal end 92 _(d), or both with thewires 132 can be helpful. This can be achieved by increasing X todecrease A₉₂. Example ranges of X, for use in the equation

${A_{92} = {\cos^{- 1}\left( \frac{X*L_{c}}{L_{i}} \right)}},$include X≥1.03, X≥1.05, X≥1.1, X≥1.15, or X≥1.2.

Angles A_(di) and A_(du) at the distal end 92 _(d) of the support-rib 92can be selected, and formed by shape of the stamp 171 described below,for desired blocking of the channels 93 during deposition, WGPdurability, and reduced manufacturing cost. A_(di) is an internal anglebetween the inner-side 92; and the distal end 92 _(d). A_(du) is aninternal angle between the upper-side 92 _(u) and the distal end 92_(d).

For example, A_(di) and A_(du) can be close to 90° as shown in FIGS.9-10. This design can improve support-rib 92 durability and can reducestamp 171 cost. Alternatively, as illustrated in FIG. 11, A_(di) can be<90° (e.g. A_(di)<90°, A_(di), ≤80°, A_(di)≤70°, A_(di)≤60°, orA_(di)≤50°; and A_(di)≥10°); and A_(du) can be >90° (e.g. A_(du)>90°,A_(du)≥100°, A_(du)≥110°, A_(du)≥120°, A_(du)≥130°; and A_(du)≤180°),thus extending the inner-side 92 at the distal end 92 _(d) over thechannel 93. This design can improve blocking of the face 11 _(f) of thesubstrate 11 during deposition of the wires 132.

Channel angle A_(c) is illustrated in FIGS. 9 and 11. The channel angleA_(c) is an angle between sides 92 _(i) and 92 _(u) of the support-ribs92 and the face 11 _(f) of the substrate 11 in the channels 93. Asillustrated in FIG. 9, in each channel 93, one channel angle A_(c) canbe <90° and the other channel angle A_(c), on an opposite side of thechannel, can be >90°. Alternatively, as illustrated in FIG. 11, in eachchannel 93, both channel angles A_(c) can be≈90°, such as for example90°+/−5°, 90°+/−10, 90°+/−15°, or 90°+/−20°. The embodiment of FIG. 11,with both channel angles A_(c)≈90°, may be preferred due to increasedperformance resulting from increased channel 93 depth.

The following further describes how the aforementioned angles aredefined or interpreted. Any angle described as an “external angle” ismeasured external to the support-rib 92. As illustrated in FIG. 12, ifthe sides 92 _(i) and 92 _(u) are curved, then side-line 121 is used todetermine angles A_(pi) and A_(pu). Side-lines 121 are aligned with anarrowest dimension of the side 92 _(i) or 92 _(u) and at an angle toalign with an average direction of the side 92 _(i) or 92 _(u). Ifangles A_(pi) and A_(pu) cannot be precisely and repeatedly determinedacross the optical device, such as due to curvature of the substrate orroughness of the face 11 _(f) of the substrate 11, then these anglesA_(pi) and A_(pu) are measured at a substrate-line 123 extending througha core of the substrate 11. The substrate-line 123 has a direction thatis an average of the face 11 _(f) of the substrate 11, or an average ofa side 11 _(s) of the substrate 11 opposite of the face 11 _(f),whichever has the smoothest surface. If the distal end 92 _(d) iscurved, then distal-line 122 is used to determine angles A_(di) andA_(du). Distal-line 122 extends between locations where the twoside-lines 121 exit the distal end 92 _(d).

In summary, distance L_(c), distance L_(i), angle A₉₂, value X in theequation

${A_{92} = {\cos^{- 1}\left( \frac{X*L_{c}}{L_{i}} \right)}},$and angles A_(di) and A_(du) at the distal end 92 _(d), can be selectedfor partial or complete blocking of the face 11 _(f) of the substrate 11in the channels 93 by the support-ribs 92 as viewed from perpendicularto the face 11 _(f) of the substrate 11. See line 94 in FIG. 9,indicating this complete blocking. Complete blocking of the channels 93,as viewed from perpendicular to the face 11 _(f) of the substrate 11,can result in negligible or no wires 132 on the inner-side 92 _(i) ofeach support-rib 92, on the substrate 11 in the channels 93, or both, asillustrated in FIG. 13.

Alternatively, as illustrated in FIG. 14, the wires 132 can enter thechannels 93 and cover part of the inner-side 92 _(i) of each support-rib92, part of the substrate 11 in the channels 93, or both. For example,≥50%, ≥75%, or ≥90% of the inner-side 92 _(i) of each support-rib 92,the substrate 11 in the channels 93, or both can be free of material ofthe wires 132, and the other portion can be coated with the wire 132.

If the wire 132 does cover part of the inner-side 92 _(i), part of thesubstrate 11 in the channels 93, or both, it can cover it with a smallthickness due to blocking effect of the slanted support-ribs 92. Forexample, Th_(132i)≤10 nm, Th_(132i)≤20 nm, or Th_(132i)≤50 nm, whereTh_(132i) is a maximum thickness of the wires 132 on the inner-sides 92_(i), measured perpendicular to the inner-side 92 _(i). As anotherexample, Th_(132u)/Th_(132i)≥2, Th_(132u)/Th_(132i)≥5,Th_(132u)/Th_(132i)≥10, Th_(132u)/Th_(132i)≥20, where Th_(132u) is amaximum thickness of the wire 132 on the upper-side 92 _(u), measuredperpendicular to the upper-side. As another example,Th_(132u)/Th_(132s)≥2, Th_(132u)/Th_(132s)≥5, Th_(132u)/Th_(132s)≥10, orTh_(132u)/Th_(132s)≥20, where Th_(132s) is a maximum thickness of thewire 132 on the face 11 _(f) of the substrate 11 in a channel 93adjacent to the support-rib 92, measured perpendicular to the face 11_(f) of the substrate 11.

As illustrated in FIGS. 15-16, the WGP 150 and 160 can further comprisea cap 152 sandwiched at least partly between each wire 132 and eachsupport-rib 92. A purpose of the cap 152 is to further close off thechannel during deposition of the wire 132. Thus, the cap 152 can help tocompensate for manufacturing limitations of support-rib 92 length L_(i)and angle A_(pi). For example, there can be limited wicking of theuncured layer 172 into the stamp 171, thus limiting a depth ofstamp-channels 173 (FIGS. 17-18). This limitation can be compensated forby use of the cap 152. Another benefit of the longer support-rib 92 pluscap 152 combination is that this can increase channel 93 length and thusprovide a larger region with a reduced effective index of refraction asdescribed in U.S. Pat. No. 6,122,103. It can be helpful for the cap 152on each support-rib 92 to be separate from (i.e. not touch) the caps 152on adjacent support-ribs 92. This separation can facilitate depositionof separate wires 132.

As illustrated in FIG. 15, the cap 152 can cover part or all of theupper-side 92 _(i), part or all of the distal end 92 _(d), or both. Asillustrated in FIG. 16, the cap 152 can cover at least part of theinner-side 92 _(i) of each support-rib 92. For example, ≥50%, ≥75%, or≥90% of the inner-side 92 _(i) of each support-rib 92 can be free ofmaterial of the cap 152, and the other portion can be coated with thecap 152.

Example maximum thicknesses Th_(152i) of the cap 152 on the inner-sides92 _(i), measured perpendicular to the inner-side 92 _(i), includeTh_(152i)≤5 nm, Th_(152i)≤10 nm, or Th_(152i)≤20 nm. As another example,Th_(152u)/Th_(152i)≥2, Th_(152u)/Th_(152i)≥5, Th_(152u)/Th_(152i)≥10,Th_(152u)/Th_(152i)≥20, where Th_(152u) is a maximum thickness of thecap 152 on the upper-side 92 _(u), measured perpendicular to theupper-side 92 _(u).

Second Method, FIGS. 9-23

A second method of making an optical device, such as a wire gridpolarizer (WGP), can comprise some or all of the following steps, whichare illustrated in FIGS. 17-23. The second method can be performed inthe following order or other order if so specified. Some of the stepscan be performed simultaneously unless explicitly noted otherwise in theclaims. There may be additional steps not described below. Theseadditional steps may be before, between, or after those described.Components of the optical device, and the optical device itself, canhave properties as described above. Any additional description ofproperties of the optical device in the below second method, notdescribed above, can be applicable to the above described opticaldevice.

The second method can comprise some or all of the following: (a) step170, applying an uncured layer 172 on a face 11, of a substrate 11 (FIG.17); (b) step 180 or 210, imprinting a pattern of uncured support-ribs182 in the uncured layer 172 (FIGS. 18 & 21); (c) step 190 or 220,curing the uncured layer (FIGS. 19 & 22); (d) depositing a cap 152 onthe upper-side 92 _(u) and the distal end 92 _(d) of each support-rib 92(FIGS. 15 & 16); and (e) depositing a wire 132 on the upper-side 92 _(u)of each support-rib 92, on the distal end 92 _(d) of each support-rib92, or both (FIGS. 13-16).

(b) & (c): Imprinting the pattern of support-ribs 92 in the uncuredlayer 172 can be performed, such as for example with the stamp 171 asdescribed below, to produce leaning support-ribs 92, which can haveangles as described above.

As illustrated in FIGS. 18 and 21, imprinting can include pressing astamp 171 into the uncured layer 172. The stamp 171 can includestamp-ribs 171 mating with the channels 93 and stamp-channels 173 matingwith the support-ribs 92.

Due to the leaning shape of the support-ribs 92, it can be difficult toremove the stamp 171 from the support-ribs 92 without damaging them. Onemethods for removing the stamp 171 from the optical device withoutdamaging the support-ribs 92 is removing the stamp 171 at an angle A₁₇₁(see FIG. 20), which can be close to A₉₂ (see FIGS. 9-12). For example,A₁₇₁ can be within 2°, 5°, 10°, 20°, or 30° of A₉₂.

Other methods for removing the stamp 171 from the optical device withoutdamaging the support-ribs 92 are using a stamp 171 that is flexible,using support-ribs 92 that are flexible, or both. The stamp 171 caninclude an elastic material. The stamp-ribs 171 _(r), a base 171 _(b) ofthe stamp 171 attached to the stamp-ribs 171 _(r), or both can beelastic. The stamp-ribs 171 _(r), a base 171 _(b) of the stamp 171attached to the stamp-ribs 171 _(r), or both can comprise polyimide,polydimethylsiloxane, or both. The stamp-ribs 171 _(r), a base 171 _(b)of the stamp 171 attached to the stamp-ribs 171 _(r), the support-ribs92 when the stamp 171 is removed from the support-ribs 92, orcombinations thereof can have a modulus of elasticity ≤6 GPa, ≤3 GPa, ≤1GPa, or ≤0.1 GPa; and can be ≥0.1 GPa, ≥0.01 GPa, ≥0.005 GPa, ≥0.001GPa, or >0.0001 GPa. The support-ribs 92 can be flexible by partiallycuring the uncured layer 172, removing the stamp 171, then finalizingthe cure. The partially-cured support-ribs 92 can flex as the stamp 171is removed.

(c) Curing the uncured layer 172 can including curing the uncuredsupport-ribs 182 into support-ribs 92 that are solid and cured. In oneembodiment, the uncured layer 172 can be a liquid with solid inorganicnanoparticles dispersed throughout a continuous phase, the solidinorganic nanoparticles including metal atoms bonded to reactive groups,where each reactive-group is independently —Cl, —OR², —OCOR², or—N(R²)₂, and R² is an alkyl group; and curing can include reacting themolecules to form a solid of the metal atoms interconnected with eachother. In another embodiment, the uncured layer 172 can be a liquid withsolid inorganic nanoparticles dispersed throughout a continuous phase;and curing can include forming a solid, interconnecting network of theinorganic nanoparticles. In another embodiment, the uncured layer 172can be a colloidal suspension including a dispersed phase and acontinuous phase; and curing the uncured layer 172 can include removingthe continuous phase.

(d) & (e): The cap 152, the wires 132, or both can be deposited bysputter deposition, which can facilitate deposition of separation of thecaps 152, the wires 132, or both on separate support-ribs 92. Theseparation of the caps 152, the wires 132, or both on separatesupport-ribs 92 can improve WGP performance, such as for exampleincreased transmission of the desired polarization (e.g. increase Tp)and reduced transmission of the opposite polarization (e.g. decreaseTs). Sputter deposition of the cap 152 can also result in the cap 152having a linear profile 152 _(L) facing the support-rib 92 and a curvedprofile 152 _(C) facing the wire 132, which can improve WGP performance.This linear profile 152 _(L)/curved profile 152 _(C) can also canimprove WPG performance. Deposition of the cap 152, the wires 132, orboth can include normal angle deposition, or can even be performedsolely by normal angle deposition, Some manufacturing facilities lackequipment for oblique angle deposition, thus such normal angledeposition can allow reduced cost manufacture of WGPs due to avoidanceof purchase of additional equipment.

(b) to (e): As illustrated in FIGS. 11 and 18-20, adjacent support-ribs22 and 92 can be connected at the proximal end 92 _(p) by material 111of the support-ribs 92. This can be accomplished by not pressing thestamp 171 all the way to the substrate. This connection of thesupport-ribs 92 by material 111 of the support-ribs 92 can increasestrength of the support-ribs 92, which can be particularly helpful inthe embodiments described herein with inclined or leaning support-ribs92. Although the support-ribs 92 might be connected at the proximal end92 _(p), each support-rib 92 can be separate from (i.e. not touch)adjacent support-ribs 92 at the distal end 92 _(d) and at the sides 92_(i) and 92 _(u). This separation can facilitate deposition of separatecap 152, separate wires 132, or both.

The uncured layer 172, the support-ribs 92, the cap 152, or combinationsthereof can have a low index of refraction for improved opticalperformance, such as for example ≤1.1, ≤1.2, ≤1.3, or ≤1.4. In oneembodiment, such index of refraction can be 1.0.

One way of achieving this low index of refraction is to include smallvoids or cavities in the uncured layer 172, which can remain in thesupport-ribs 92. These small voids, filled with air, can lower theoverall index of refraction. For example, the support-ribs 92 caninclude silicon dioxide, with an index of refraction of around 1.4-1.5,but with the voids, the overall index of refraction can be <1.4. Thesevoids can be formed by use of a solvent in the uncured layer 172 whichhas larger molecules. For example, a solvent in the uncured layer 172can have a molecular weight of ≥70 g/mol, ≥80 g/mol, ≥90 g/mol, ≥100g/mol, or ≥110 g/mol. As another example, a chemical in this solvent canhave a large number of atoms, such as for example ≥15 atoms, ≥20 atoms,or ≥25 atoms. It can be helpful for this solvent to not have too high ofa molecular weight so that it can be sufficiently volatile. Therefore,this solvent can have a molecular weight of ≤125 g/mol, ≤150 g/mol, ≤175g/mol, ≤200 g/mol, or ≤300 g/mol. This solvent can also have ≤30 atoms,≤50 atoms, or ≤75 atoms. Further, this solvent can have a structurewhich occupies larger space, such as an aryl molecule or otherwise amolecule with double bonds. For example, the uncured layer 172 caninclude benzene or xylene.

The support-ribs have a real part of a refractive index n_(S)≥1.7 orn_(S)≥2.0 and an extinction coefficient k_(S)≥0.1, across theultraviolet spectrum, across the visible spectrum, across the infraredspectrum, or combinations thereof. Example materials of the support-ribs92 include an oxide of hafnium, lead, niobium, tantalum, titanium,tungsten, zirconium, silicon or combinations thereof.

The support-ribs 92 can include organic moieties to facilitatemanufacturing, to affect WGP performance, or combinations thereof. Theseorganic moieties can be part of the material composition of the uncuredlayer 172, and can remain after the uncured layer 172 is cured to formthe support-ribs 92. For example, ≥0.1%, ≥1% and ≥25%, ≥50% of atoms inthe support-ribs 92 can be part of organic moieties. As another example,a mass percent of the organic moieties in the support-ribs can be ≥0.1%and ≤20%. The organic moieties can include —CH₃, —CH₂CH₃, or both. Asanother example, all organic moieties can include ≤3 carbon atoms.

The cap 152 can have the same or a different material compositionas/than the support-rib 92. In one embodiment, the caps 152 and thesupport-ribs 92 can comprise silicon dioxide. In one embodiment, thesupport-ribs 92 and not the caps 152 can include organic moieties due todifferent methods of deposition/formation of each (e.g. support-ribs 92typically formed by spin-on then imprint and the caps 152 typicallyformed by sputter).

The support-ribs 92, the substrate 11, and the cap 152 can have the sameor similar material composition. For example, ≥70%, ≥80%, ≥90%, or ≥95%of a material composition of the support-ribs 92, the substrate 11, andthe cap 152 can be the same. The support-ribs 92, the substrate 11, thecap 152, or combinations thereof can be transparent across theultraviolet spectrum, the visible spectrum, the infrared spectrum, orcombinations thereof. The wire 132 can be reflective, across theultraviolet spectrum, the visible spectrum, the infrared spectrum, orcombinations thereof.

As illustrated in FIG. 23, the second method can further comprise step230, including applying a conformal layer 231 on cured support-ribs 92,forming optical device 232. Step 230 can follow any of steps 190, 200,or 220. The conformal layer 231 can be applied by atomic layerdeposition. The conformal layer 231 can have a refractive index (n₂₃₁)that is higher than a refractive index (n₉₂) of the support-ribs 92.Example values of these refractive indices include: n₉₂≥1.3, n₉₂≥1.5, orn₉₂≥1.7; n₉₂≤1.6, n₉₂≤1.8, or n₉₂≤1.99; n₂₃₁≥2.0 or n₂₃₁≥2.2; andn₂₃₁≤3.0 or n₉₂≤4.0. These refractive index n₂₃₁ and n₉₂ values andrelationships can be such values and relationships across theultraviolet spectrum, visible spectrum, infrared spectrum, orcombinations thereof. If the optical device is a waveguide, addition ofthe conformal layer 231 can improve waveguide performance, especially ifn₂₃₁>n₉₂ at a wavelength or across a wavelength range of intended use.

First and Second Methods, Wire Separation

It can be useful for the wires 62 or 132 to be separate from wires 62 or132 on adjacent support-ribs 22 or 92. The following paragraphs describehow to achieve this in both the first method and the second method.

In the first method, a preferred method of deposition is sputter.Pressure in the chamber can be raised for less directional deposition,resulting in deposition of the wire 62 from all angles and preferentialdeposition of the wire 62 at a distal end D of the support-ribs 22. Adeposition pressure that is too high, however, can result in too slow ofa deposition rate. A pressure of five millitorr is suggest for balancing(a) deposition of the wire 62 from all angles by high pressure; with (b)lower pressure to improve deposition rate.

In the second method, preferred deposition methods include evaporationor low pressure sputter, either resulting in directional deposition ofthe wire 132 on the upper-side 92 _(u) and the distal end 92 _(d) ofeach support-rib 92. In evaporation or low pressure sputter, pressurecan be lowered as far as possible while still maintaining a plasma. Inthe second method, with slanted support-ribs 92, directional deposition,such as by evaporation or low pressure sputter, can facilitateseparation of wires 62 on adjacent support-ribs 92.

In the first method, the channels 41 can be partially blocked, by thecap 52 described above, to facilitate separation of wires 62 on adjacentsupport-ribs 22. In the second method, the channels 93 can be partiallyblocked, by the cap 152 described above, to facilitate separation ofwires 132 on adjacent support-ribs 92.

A shape of support-ribs 22 or 92 can help facilitate separation of wires62 or 132. The support-ribs 22 in FIGS. 2-8 are illustrated with acurved distal end D, which facilitates manufacturing, but can make itmore difficult to keep the wires 62 separate from each other. The distalend 92 _(d) of support-ribs 92 in the second method, and illustrated inFIGS. 9-10 and 13-16, have a rectangular shape, which can be moredifficult to manufacture, but can help keep wires 132 separate from eachother. The distal end 92 _(d) of support-ribs 92 in the second method,and illustrated in FIGS. 11 and 19-20, have a trapezoid shape, which canfurther assist in keeping wires 132 separate from each other. Therectangular shape of FIGS. 9-10 and 13-16 and the trapezoid shape ofFIGS. 11 and 19-20, and described above, can be applied in the firstmethod. The stamp 13 in the first method can be replaced by the stamp171 of FIGS. 17-22.

A high aspect ratio (AR) of the support-ribs 22 or 92 can helpfacilitate separation of wires 62 or 132, where AR=Th₂₂/P or AR=Th₉₂/P,Th₂₂ is a thickness of support-ribs 22, Th₉₂ is a thickness ofsupport-ribs 92, and P is a pitch of the support-ribs 22 or 92.

If the above methods are insufficient for keeping the wires 62 or 132separate, and if the wires 62 or 132 are made of aluminum, then anysmall amount of aluminum in the channels 41 or 93 can be oxidized toform aluminum oxide, thus separating pure aluminum wires 62 or 132 fromeach other. Aluminum was used as an example—oxidation can be used withother suitable materials. An isotropic etch may also be used to removeany small amount of wires 62 or 132 in the channels 41 or 93.

Third Optical Device, with Slanted Support-Ribs 92

As illustrated in FIG. 23, optical device 232 can include a conformallayer 231 on support-ribs 92. The support-ribs 92 of optical device 232are illustrated with a shape similar to the support-ribs 92 of opticaldevice 110, but these support-ribs 92 can have other shapes as describedherein. The conformal layer 231 and the support-ribs 92 can haverefractive index values as described above. If the optical device is awaveguide, addition of the conformal layer 231 can improve waveguideperformance, especially if n₂₃₁>n₉₂ at a wavelength or across awavelength range of intended use. Optical device 232 can be formed intoa WGP, such as for example with addition of a wire 132 as describedherein.

What is claimed is:
 1. A wire grid polarizer (WGP) comprising: an arrayof parallel, elongated support-ribs on a face of a substrate withchannels between adjacent support-ribs, the channels including anair-filled region extending along a length of the channels, the lengthof the channels being a longest dimension of the channels; eachsupport-rib having a cross-sectional profile with a proximal end locatedclosest to the substrate and a distal end located farthest from thesubstrate, and sides facing the channels and extending from the proximalend to the distal end; the sides of the support-ribs are inclined to oneside with all support-ribs leaning in a single direction, the sidesincluding an inner-side which leans towards and faces the substrate andan upper-side opposite of the inner-side and facing away from thesubstrate; 15°≤A₉₂≤75°, where A₉₂ is a smallest angle between a planeand the face of the substrate, the plane extending along a length ofeach support-rib through a center of the support-rib from the proximalend to the distal end; 15°≤A_(pi)≤75° and 105°≤A_(pu)≤165°, where A_(pi)is an external angle between the inner-side and the face of thesubstrate, and A_(pu) is an external angle between the upper-side andthe face of the substrate; a wire on the upper-side and the distal endof each support-rib, each wire being separate from wires on adjacentsupport-ribs; the support-ribs and the substrate are transparent, andthe wire is reflective across the ultraviolet spectrum, the visiblespectrum, the infrared spectrum, or combinations thereof; and ≥75/of theinner-side of each support-rib is free of material of the wire and ≥75%of the face of the substrate in the channels is free of material of thewire.
 2. The WGP of claim 1, wherein ≥0.1% and ≤50% of atoms in thesupport-ribs are part of organic moieties.
 3. The WGP of claim 1,wherein organic moieties there is a maximum of 15° variation of A₉₂among the support-ribs.
 4. A wire grid polarizer (WGP) comprising: anarray of parallel, elongated support-ribs on a face of a substrate withchannels between adjacent support-ribs; each support-rib having across-sectional profile with a proximal end located closest to thesubstrate and a distal end located farthest from the substrate, andsides facing the channels and extending from the proximal end to thedistal end; the sides of the support-ribs are inclined to one side, thesides including an inner-side which leans towards and faces thesubstrate and an upper-side opposite of the inner-side and facing awayfrom the substrate; 15°≤A₉₂≤75°, where A₉₂ is a smallest angle between aplane and the face of the substrate, the plane extending along a lengthof each support-rib through a center of the support-rib from theproximal end to the distal end; a wire on the upper-side and the distalend of each support-rib, each wire being separate from wires on adjacentsupport-ribs; and the support-ribs and the substrate are transparent,and the wire is reflective, across the ultraviolet spectrum, the visiblespectrum, the infrared spectrum, or combinations thereof.
 5. The WGP ofclaim 4, wherein ≥0.1% and ≤50% of atoms in the support-ribs are part oforganic moieties.
 6. The WGP of claim 4, where there is a maximum of 15variation of A₉₂ among the support-ribs.
 7. The WGP of claim 4, wherein≥75% of the inner-side of each support-rib is free of material of thewire.
 8. The WGP of claim 4, wherein ≥75% of the face of the substratein the channels is free of material of the wire.
 9. The WGP of claim 4,wherein Th_(132i)≤20 nm, where Th_(132i) is a maximum thickness of thewires on the inner-sides, measured perpendicular to the inner-side. 10.The WGP of claim 4, wherein Th_(132u)/Th_(132i)≥5, where Th_(132u) is amaximum thickness of the wire on the upper-side, measured perpendicularto the upper-side, and Th_(132i) is a maximum thickness of the wire onthe inner-side, measured perpendicular to the inner-side.
 11. The WGP ofclaim 4, wherein Th_(132u)/Th_(132s)≥5, where Th_(132u) is a maximumthickness of the wire on the upper-side of any support-rib, measuredperpendicular to the upper-side, and Th_(132s) is a maximum thickness ofthe wire on the face of the substrate in a channel adjacent to thesupport-rib, measured perpendicular to the face of the substrate. 12.The WGP of claim 4, further comprising a cap on the upper-side and thedistal end of each support-rib and sandwiched at least partly betweeneach wire and each support-rib, wherein: the cap has a differentmaterial composition than the support-rib; the cap is transparent acrossthe ultraviolet spectrum, the visible spectrum, the infrared spectrum,or combinations thereof; and the cap having a linear profile facing thesupport-rib and a curved profile facing the wire.
 13. The WGP of claim4, wherein |180°−A_(pi)−A_(pu)|≤10°, where A_(pi) is an external anglebetween the inner-side and the face of the substrate, and A_(pu) is anexternal angle between the upper-side and the face of the substrate. 14.The WGP of claim 4, wherein |A_(pi)−A_(di)|≤20° and|180−A_(pu)−A_(du)|≤20°, where A_(pi) is an external angle between theinner-side and the face of the substrate, A_(di) is an internal anglebetween the inner-side and the distal end, A_(pu) is an external anglebetween the upper-side and the face of the substrate, and A_(du) is aninternal angle between the upper-side and the distal end.
 15. The WGP ofclaim 4, wherein the face of the substrate in the channels is blocked bythe support-ribs as viewed from perpendicular to the face of thesubstrate.
 16. The WGP of claim 4, wherein 45°≤A_(pi)≤65° and115°≤A_(pu)≤135°, where A_(pi) is an external angle between theinner-side and the face of the substrate, and A_(pu) is an externalangle between the upper-side and the face of the substrate.
 17. The WGPof claim 4, wherein${{\cos^{- 1}\left( \frac{1.1*L_{c}}{L_{i}} \right)} \leq A_{92} \leq {\cos^{- 1}\left( \frac{0.3*L_{c}}{L_{i}} \right)}},$where A₉₂ is an external angle between the inner-side and the face ofthe substrate; L_(c) is a straight-line distance, from one support-ribto an adjacent support-rib in the channel, parallel to the face of thesubstrate; and L_(i) is a straight-line distance of the inner-side fromthe proximal end to the distal end.
 18. The WGP of claim 4, wherein thesupport-ribs have a real part of a refractive index n_(S)≤1.4.
 19. Amethod of making a wire grid polarizer (WGP), the method comprising:applying an uncured layer on a face of a substrate; imprinting a patternof uncured support-ribs in the uncured layer, wherein 15°≤A₁₂≤75°, whereA₁₂ is a smallest angle between a plane and the face of the substrate,the plane extending along a length of each support-rib through a centerof the support-rib from the proximal end to the distal end; curing theuncured layer, including curing the uncured support-ribs intosupport-ribs that are solid and cured; and depositing a wire on theupper-side and the distal end of each support-rib, each wire beingseparate from wires on adjacent support-ribs.
 20. The method of claim19, wherein depositing the wire includes normal angle deposition.